Solved

Complex Numbers in C

Posted on 2007-11-26
6
360 Views
Last Modified: 2010-04-15
Could someone give me sone help on working out complex root using C?

Here is my code so far:
#include <stdio.h>
#include <math.h>

double t1=0,t2=0,t3=0;
double quad1(double t1,double t2, double t3);
double quad2(double t1,double t2, double t3);

main()
{
      printf("Enter the X square coeff: ");
      scanf("%lf",&t1);
      printf("Enter the X coeff: ");
      scanf("%lf",&t2);
      printf("Enter the last term: ");
      scanf("%lf",&t3);

      printf("The 2 solutions of your equation are: %lf and %lf",quad1(t1,t2,t3),quad2(t1,t2,t3));

}

double quad1(double t1,double t2, double t3)
{
      double ans1=0,det1=0;

      det1= pow(t2,2) - (4*t1*t3); // b^2 - 4ac
      ans1= (((-1)*t2) + pow(det1,0.5))/(2*t1);
      return(ans1);
}

double quad2(double t1,double t2, double t3)
{
      double ans2=0,det2=0;
      
      det2= pow(t2,2) - (4*t1*t3); // b^2 - 4ac
      ans2= (((-1)*t2) - pow(det2,0.5))/(2*t1);
      return(ans2);
}

As you can see, it only works out real roots

Cheers
0
Comment
Question by:jonnytabpni
  • 3
  • 2
6 Comments
 
LVL 45

Accepted Solution

by:
Kdo earned 500 total points
ID: 20349823
Hi jonnytabpni,

The C math routines that you're using (pow) doesn't deal with imaginary numbers.  To get the results you seek, you'll need to determine if the result will be real or imaginary, set a flag accordingly, and if imaginary, pass the absolute value of the data item.

The result is that the function will always return the root value, and you'll indicate in a separate field whether the result is real or imaginary.


Good Luck,
Kent
0
 

Author Comment

by:jonnytabpni
ID: 20349946
ok fair enough but im confused how to actually work out the complex roots once iv passed the data onto a seperate function.

cheers
0
 
LVL 45

Expert Comment

by:Kdo
ID: 20349993
Hi jonnytabpni,

There are several ways to do this, though they all require a bit of effort.

C functions return one value.  Period.  So you can't get the function to return the real root and a real/imaginary flag.  The two most common ways around this are to return one or both values via function parameters, or to build a 'complex' structure that contains a the two critical components and pass it to the function.

typedef struct
{
  int    Imaginary;
  rel   Value;
) compex_t;



Good Luck,
Kent
0
What Should I Do With This Threat Intelligence?

Are you wondering if you actually need threat intelligence? The answer is yes. We explain the basics for creating useful threat intelligence.

 

Author Comment

by:jonnytabpni
ID: 20350368
ok i've got it:

#include <stdio.h>
#include <math.h>

double a,b,c;
int find_roots(double,double,double,double*,double*);

main()

{
      double x1,x2;
      int type;


      
      printf("Enter the 3 quadratic coeffs: ");
      scanf("%lf %lf %lf",&a,&b,&c);



      type = find_roots(a,b,c, &x1,&x2);

      if(type==0)
      {
            printf("The 2 solutions of your equation are: %lf and %lf",x1,x2);
            if((((-1)*b)/a) == (x1+x2)) printf("\nCheck Confirmed!"); //Check to see if real roots are correct
      }
      else
      {
            printf("The 2 complex roots of your equations are %lf + j%lf and %lf - j%lf",x1,fabs(x2),x1,fabs(x2));
      }


}


int find_roots(double a,double b, double c,double *x1,double *x2)

{

      double ans1=0,det=0;

      det= pow(b,2) - (4*a*c); // b^2 - 4ac
      
      if(det>0)
      {
            det = sqrt(det);

            *x1 = ((-1)*(b))/(2*a) + (det/(2*a));
            *x2 = ((-1)*(b))/(2*a) - (det/(2*a));
            return(0);
      }
      else
      {
            *x1 = ((-1)*(b))/(2*a);
            *x2 = det/(2*a);
            return(1);
      }
}

the only thing i need now is a way to check to see if the comple roots are correct
0
 
LVL 45

Expert Comment

by:Kdo
ID: 20350641
Hi jonnytabpni,

That should be pretty easy to do.  Build several test cases of known values.

 4  ^  2
 9  ^  2

 4  ^  1/2
 9  ^  1/2

If the values are correct (and they should be) rerun the test with negative coefficients.

Then, just to make sure:

  27 ^ 1/3
 -27 ^ 1/3


Good Luck,
Kent
0
 
LVL 5

Expert Comment

by:mandelia
ID: 20356731
Have you Looked into Complex.h.
0

Featured Post

How to run any project with ease

Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
- Combine task lists, docs, spreadsheets, and chat in one
- View and edit from mobile/offline
- Cut down on emails

Join & Write a Comment

This tutorial is posted by Aaron Wojnowski, administrator at SDKExpert.net.  To view more iPhone tutorials, visit www.sdkexpert.net. This is a very simple tutorial on finding the user's current location easily. In this tutorial, you will learn ho…
How to Win a Jar of Candy Corn: A Scientific Approach! I love mathematics. If you love mathematics also, you may enjoy this tip on how to use math to win your own jar of candy corn and to impress your friends. As I said, I love math, but I gu…
Video by: Grant
The goal of this video is to provide viewers with basic examples to understand and use for-loops in the C programming language.
The goal of this video is to provide viewers with basic examples to understand and use conditional statements in the C programming language.

747 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

12 Experts available now in Live!

Get 1:1 Help Now